Screen and recoat involves roughing up the surface of the existing finish, so that the new finish layer will adhere and not peel away. Since the old finish is still intact across the whole floor, regular upkeep of the finish will not only restore the shine, but it also may indefinitely postpone the need to sand the floor, so your floor will last longer. This is particularly important for engineered hardwood, where the wear layer may only be thick enough to start with for two cycles of sanding before you would have to replace the floor.
There are a number of reasons to sand away the finish completely and apply a brand new finish from scratch:
Sanding floors is better left to professionals with experience. Each step of the refinishing process depends on an even sanding job.
Many DIYers are dismayed to realize that every imperfection in the sanding job appears magnified and even more visible once the finish is applied. A professional will also be able to sand floors while removing the minimum amount of wood (approximately 1/32"), allowing for future sanding and refinishing and greater stability of the floor boards. Sanding is not a one step process.
It is a step-down process, using progressively finer sandpaper to remove the scratch marks of the previous grit. The rougher, starting grit (often 36, but it depends on the floor) is designed to remove the old finish, and the subsequent grits,going up to 100 or 120, remove the scratch marks of the previous grit level, to create a smooth and level surface for the finishing. Professional floor refinishers use a drum sander for the main area of the room, and an edger for the edges. Corners can be scraped out by hand with a scraper, and then hand screened with a 100 or 120 grit paper to match it to the rest of the floor.
If you are going to sand your own floors, it is very important to pay attention to these three things:
Whatever course of action you choose, you have to remember that damages are harder to fix than if the job had been done right to begin with. If you're not sure you can do it yourself, hire a professional wood floor refinishing company like Hardwood Revival. With years of experience and the right equipment, you'll get the best results possible for your precious floor.